Pitot tube



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Patented Oct. 11, 1927.

UNITED STATES PATENT OFFICE.

HARRY WILLIAM BROADY, OF NEW YORK, N. Y., AND GUSTAV GEORG HERMAN RYD- BERG, OF APPELVIKEN, SWEDEN, ASSIGNORS TO SVENSKA AKTIEBOLAGET LOGG, OF STOCKHOLM, SWEDEN, .A CORPORATION OF SWEDEN.

PITOT TUBE.

Application led April 12, 1926. Serial No. 101,559.

In hydrostatic logs so called Pitot-tubes are used, as well known, which tubes in operative position extend outside the hull and are adapted to transmit the water pressure created bythe velocity of the ship to an indicating device, from which the velocity of the ship thus may be read off. Such tubes hitherto generally have been Vmade of brass in order not to be damaged by the corrosive action of the water. Experience, however, has proved that the tubes after some time, longer or shorter, will break off, even if the dimensions of the tube are such, that the tube would be able to withstand the pressure exerted by the water. The breaking off of the tube is explained by the fact that the tube during the running of the ship is uninterruptedly subjected to vibrations,which gradually change the structure of the metal into a crystalline state,f which renders the tube brittle. Efforts have been made to prevent the breakingof by strengthening the tube but hitherto no practical means in this respect have been devised.

In order to procure a Pitot-tube the character of which is not changed, at least not in an essential degree, the tube is, according to this invention, composed of a strength member, preferably in the shape of a tube of steel or any other suitable material such as Monel-metal, and members made of brass or other suitable non-corrosive material, which will protect the said strength member against the corrosive action of the water.

The accompanying drawing shows in a longitudinal section a Pitot-tube arranged in accordance with the preferred form of execution of this invention. The drawing shows only the tube, members mounted in which the tube` is slidingly Vmounted and means for fixing the tube in operative and y inoperative positions being omitted, as they do not belong to the invention.

The Pitot-tube shown in the drawingas an example consists of a tube l of steel, which is covered on its inner side with a the same as well as the casing or fr'amein' tube 2 andon its outer side with a tube 3 both of brass, phosphor-bronze or any other metal which is able to resist the corrosive action ofthe water. The said tubes or covers 2 and 3 will protect the steel tube 1 against the water, so that it does not rust. The brass tubes, evidently, must cover only such parts of the steel tube, as otherwise would come into contact with the water. Owing to the known qualities of steel the tube l will well withstand the outer pressure of the water. The vibrations, to which it is subjected, will practically not affect the steel in any essential' degree and in any case 1n a much slighter degree than brass or bronze. At the mounting of the Pitottube 1n the ship, its length must be adapted to the thickness of the bottom of the hull and other conditions, in consequence whereof the cutting off operation generally is eifected on board the ship. Together with the tube a mouth-piece 4 of the shown construction is delivered, which, after the tube has been cut to the proper length, 1s soldered to the same. In special cases the tube may be delivered with the mouth piece fixed to the same. The said brass covers may be applied in any suitable manner for instance by drawing, rolling or soldering.

We claim:

1. A Pitot-tube having a strength member and protective members covering the same, said members being able to resist the corrosive action of the water.

2. 'A Pitot-tube comprising a tube or" steel and inner and outer covers therefor of a metal' able to resist the corrosive action of water.

3. A Pitot-tube comprising a tube of steel, an inner tube and an outer tube both of brass and covering the said tube of steel and protecting the same against. the corrosive action of water.

In testimony whereof we have atxed our` signatures.

HARRY WILLIAM BROADY. GUSTAV GEORG HERMAN RYDBERG. 

